Amine vapor curable coating composition of an acrylic polymer and a polyisocyanate

ABSTRACT

A coating composition that can be cured with a vaporous amine catalyst, cured by baking at elevated temperatures or can be cured at ambient temperatures which has as the binder 
     A. an acrylic polymer containing hydroxyl groups and amine containing groups and has a weight average molecular weight of about 2,000-50,000 and 
     B. an aliphatic polyisocyanate.

BACKGROUND OF THE INVENTION

This invention is related to a coating composition and in particular toa coating composition that can be cured with an amine vapor catalyst.

In modern automobiles and trucks, flexible plastic composites and rubbertype substrates are used, for example, for fenders, bumpers, flexiblefiller panels located between the bumper and the chassis, flexiblefender extension around headlights and tail lights and for otherflexible exterior trim parts. All of these substrates have the samecommon problem which is that these substrates cannot withstand thebaking temperatures required for curing conventional automotive paints.Paints of two reactive components have been used in which the componentsare mixed just prior to application which is a cumbersome technique foran automotive and truck assembly plant. Some low temperature bake paintshave been used with success. But there is a need for a versatile paintor coating composition that can be fully cured rapidly at ambienttemperatures using a vaporous catalyst or baked at low temperatures fora short period of time or cured at ambient temperatures within arelatively short time period.

Vapor curing of coating compositions is well known in the art as shownby Blegan U.S. Pat. No. 4,517,222 issued May 14, 1985 and McInnes et al.U.S. Pat. No. 3,874,898 issued Apr. 1, 1975. However, the compositionsshown by these patents are not adequate for automotive and truckmanufacturing uses.

SUMMARY OF THE INVENTION

A coating composition curable by a vaporous amine catalyst and containsabout 20-80% by weight of film forming binder and correspondingly,80-20% by weight of a liquid carrier; the binder, is a blend of

A. an acrylic polymer containing hydroxyl groups and amine containinggroups of secondary amine groups, tertiary amine groups, pyridinegroups, aminoester groups, hydroxy amino ester groups and the polymerhas a weight average molecular weight of about 2,000-50,000; and

B. an aliphatic polyisocyanate;

compositions of the above type that are curable by baking and curable atambient temperatures also are a part of this invention.

DETAILED DESCRIPTION OF THE INVENTION

The coating composition forms a high quality clear or pigmented finishover flexible substrates such as flexible plastic composites and rubbersused in the manufacture of automobiles and trucks. These flexiblesubstrates are used as fenders, filler panels, side panels, fenderextensions, moldings and other trim parts. The flexible substrates canbe hydrocarbon rubbers such as ethylene/propylene,ethylene/propylene/diene polymers, terpolymer elastomers, polyvinylchloride, chlorinated rubbers, chloro-sulfonated rubber,acrylonitrile/butadiene/styrene polymers, urethane foamed elastomers,thermoplastic urethanes, crystalline amorphous polyamides, reactioninjection molded urethanes and the like. The finish has excellentadhesion to the substrate and is hard, flexible, durable and can bebuffed to remove imperfections in the finish and can be sanded forsubsequent refinishing.

The coating composition does not require baking at conventional hightemperatures used for automotive paints but can be cured with an aminevapor catalyst. Curing without a vaporous amine catalyst can beaccomplished at low baking temperatures of about 50°-100° C. for about 5to 30 minutes. Also, the composition can be cured at ambienttemperatures. Under ambient temperature conditions, the coating becomestack free in about 10 and 30 minutes and is cured in about 24 hours.

Preferably, the coating composition has as the binder about 40-90% byweight of the acrylic polymer and 10-60% by weight of an aliphaticpolyisocyanate.

The acrylic polymer contains both hydroxyl groups and amine containinggroups which are secondary amine groups, tertiary amine groups, pyridinegroups, aminoester groups and hydroxy amino ester groups.

The polymer has a weight average molecular weight of about 2,000-50,000and preferably about 5,000-20,000. Molecular weight is determined by gelpermeation chromatography using polymethyl methacrylate as the standard.

The acrylic polymer is composed of polymerized monomers of (1) an alkylmethacrylate or an alkyl acrylate or mixtures thereof where the alkylgroups have 1-12 carbon atoms, (2) hydroxy alkyl acrylate or hydroxyalkyl methacrylate or mixtures thereof where the alkyl groups have 2-4carbon atoms and (3) ethylenically unsaturated amine containingmonomers. The acrylic polymer can contain 0.1-50% by weight of styrene.

The acrylic polymer preferably contains polymerized monomers of about

(1) 10-30% by weight, based on the weight of the acrylic polymer, ofstyrene or methyl methacrylate,

(2) 1-25% by weight, based on the weight of the acrylic polymer, of anamine containing ethylenically unsaturated monomer,

(3) 30-70% by weight, based on the weight of the acrylic polymer, ofalkyl methacrylate, alkyl acrylate or mixtures thereof, each having 2-12carbon atoms in the alkyl group, and

(4) 20-40% by weight, based on the weight of the acrylic polymer, ofhydroxy alkyl acrylate or methacrylate, each having 2-4 carbon atoms inthe alkyl group.

Typical alkyl acrylates and methacrylates that can be used to form theacrylic polymer are as follows: methyl methacrylate, ethyl methacrylate,propyl methacrylate, butyl methacrylate, pentyl methacrylate, hexylmethacrylate, octyl methacrylate decyl methacrylate, laurylmethacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, butylacrylate, octyl acrylate, nonyl acrylate, decyl acrylate, laurylacrylate and the like. Other polymerizable monomers that can be used arestyrene, vinyl toluene, acrylamide, methacrylamide, about 0.1-5% byweight of an ethylenically unsaturated carboxylic acid such asmethacrylic acid, acrylic acid, itaconic acid. Also, maleate andfumarate esters and esters of itaconic acid can be used.

Typical hydroxy alkyl acrylates and methacrylates that can be used toform the acrylic polymer are as follows: hydroxy ethyl acrylate, hydroxypropyl acrylate, hydroxy butyl acrylate, hydroxy ethyl methacrylate,hydroxy propyl methacrylate and hydroxy butyl methacrylate. Chainextended hydroxy monomers can be used such as caprolactone adducts ofthe above hydroxy monomer. One useful adduct is of caprolactone andhydroxy ethyl acrylate.

Typical ethylenically unsaturated monomers containing amine groups thatcan be used to form the acrylic polymer are as follows: t-butyl aminoethyl methacrylate, diethyl amino ethyl methacrylate, ethyl methylaminoethyl methacrylate, t-butyl amoniethyl acrylate, diethylamino ethylacrylate, ethyl methyl amino ethyl methacrylate, dimethyl amino ethylmethacrylate and dimethyl amino ethyl acrylate, vinyl pyridine, e.g., 2and 4 vinyl pyridine and vinyl imidazole.

Amino ester groups can be attached to the acrylic polymer by forming theacrylic polymer by forming the acrylic polymer with acrylic acid,methacrylic acid and the like and post reacting the acid, with analkylene imine such as propylene imine to provide amino ester groupspendent from the carbon-carbon polymer backbone of the formula ##STR1##where R is an alkylene group having 2-3 carbon atoms.

The acrylic polymer can contain hydroxy aminoester groups by forming thepolymer with glycidyl acrylate or glycidyl methacrylate and thenreacting with ammonia. The acrylic polymer and ammonia are charged intoa pressure vessel and heated to about 80°-150° C. and maintained at apressure of abut 14-35 kilograms per square centimeter (approximately200-500 pounds per square inch) for about 1 to 8 hours or until all ofthe glycidyl groups have been reacted with ammonia. After the reactionof ammonia with the glycidyl groups of the polymer is completed, excessfree ammonia is vacuum stripped off. The resulting acrylic polymer hashydroxy amino ester groups pending from the backbone of the polymer.

A preferred acrylic polymer prepared by this method contains about40-50% by weight methyl methacrylate, 25-45% by weight of an alkylacrylate or methacrylate such as butyl methacrylate or laurylmethacrylate and 5-20% by weight glycidyl methacrylate or glycidylacrylate that has been reacted with ammonia to form hydroxy amino estergroups pendent from the carbon-carbon polymer backbone of the formula##STR2##

Another preferred acrylic polymer contains styrene, ethyl methacrylate,lauryl methacrylate, hydroxy ethyl acrylate and methacrylic acid postreacted with propyleneimine or ethyleneimine to provide amino estergroups.

Another preferred acrylic polymer contains styrene, ethyl methacrylate,lauryl methacrylate, hydroxy ethyl acrylate and butyl amino ethylmethacrylate.

Still another preferred acrylic polymer contains styrene, vinylpyridine, ethyl methacrylate, lauryl methacrylate and hydroxy ethylacrylate.

The polymerization of the monomers to form the acrylic polymer iscarried out by conventional techniques in which the monomers, solventsand polymerization catalyst are charged into a polymerization vessel andreacted at about 50°-200° C. for about 0.5-6 hours to form the polymer.

Typical polymerization catalysts that are used areazobisisobutyronitrile, azo-bis(gamma dimethyl valeronitrile),azo-bis(cyclohexane carbonitrile) are the like.

Typical solvents used are tolune, xylene, ethyl acetate, acetone, methylethyl ketone, methyl isobutyl ketone, ethanol, isopropanol and otheraliphatic, cycloaliphatic and aromatic hydrocarbon esters, ethers,ketones and alcohols as are conventionally used.

Typical aliphatic polyisocyanates that are used in the coatingcomposition are as follows: isophorone diisocyanate which is3-isocyanatemethyl-3,3,3-trimethyl-cyclohexyl-isocyanate,propylene-1,2-diisocyanate, butylene-1,2-diisocyanate,butylene-1,3-diisocyanate, hexamethylene diisocyanate,methyl-2,6-diisocyanate, methyl-2,6-diisocyanate caproate, octamethylenediisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, nonamethylenediisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, decamethylenediisocyanate, 2,11-diisocyano-dodecane and the like; cycloaliphaticpolyisocyanates are included under the term aliphatic polyisocyanatesand are as follows: 2,2-methylene-bis-(cyclohexyl isocyanate),3,3'-methylene-bis-(cyclohexyl isocyanate),4,4'-methylene-bis-(cyclohexylisocyanate), 4,4'-ethylene-bis-(cyclohexylisocyanate), 4,4'-propylene-bis-(cyclohexyl isocyanate).

One particularly preferred aliphatic polyisocyanate that forms a highquality finish is the trimer of hexamethylene diisocyanate.

The coating composition may contain about 0.01-2.0% by weight, based onthe weight of binder, of a curing catalyst. The catalysts are usuallyorgano metallics such as dibutyl tin dilaurate, zinc octoate, dibutyltin di-2-ethylhexoate, stannous octoate, stannous oleate, zincnaphthenate, vanadium acetyl acetonate, and zirconium acetyl acetonate.Stannous octoate is a preferred catalyst.

The coating composition of this invention can be applied by any of theconventional application methods, such as spraying, electrostaticspraying, dipping, brushing, flow-coating and the like. The viscosity ofthe composition can be adjusted for any of these methods by addingsolvents if necessary. Generally, the composition is utilized at a highsolids content which keeps air pollution at a minimum level.

After application of the composition to a substrate, the composition canbe cured rapidly by exposure to an amine vapor catalyst for about 1 to 4minutes at a temperature of about 10° C. to 50° C. This can beaccomplished by placing the substrate coated with a composition in achamber containing a high concentration of amine catalyst vapors.Usually, the amine vapors are at a concentration of about 500-3,000 ppm.Alternatively, the amine catalyst vapors may be sprayed to the substrateas the composition is being applied.

After exposure to the amine catalyst, the coated substrate is temperedwith a turbulant air stream at about 10°-60° C. to remove excess aminefrom the coating.

Typical amine catalysts that can be used are as follows: tertiary aminescontaining substituents such as alkyl, alkanol, aryl, cycloaliphatic,and mixtures of such substituents. Additionally, heterocyclic tertiaryamines may be suitable for use in the invention also. Representativetertiary amines include, for example, triethyl amine,dimethylethylamine, trimethyl amine, tributyl amine, dimethyl benzylamine, dimethyl cyclohexyl amine, dimethyl ethanol amine, diethylethanol amine, triethanol amine, pyridine, 4-phenylpropyl pyridine,2,4,6-collidone, quinoline, isoquinoline, N-ethyl morpholine,triethylene diamine, and the like and mixtures thereof. Additionally, itis conceivable to use amine oxides and quaternary ammonium aminesdepending upon the practicality of providing such amines in the vaporousphase. A myriad of proprietary tertiary amine catalysts currently areavailable and should function in the process additionally. One preferredcatalyst is dimethyl ethanol amine.

Particularly thick coatings of the coating composition can be rapidlycured with the amine catalyst such as coatings 5-20 mils in thickness.It is believed that the presence of the amine groups in the acrylicpolymer in combination with the hydroxyl groups provides for rapidcuring of thick coatings which cannot be accomplished with prior artcompositions.

The coating composition can contain pigments in a pigment to binderweight ratio of about 1/100 to 400/100. These pigments can be introducedinto the composition by first forming a mill base with the acrylicpolymer utilized in the composition or with other compatible polymers orpolymer dispersants by conventional techniques, such as sand-grinding,ball milling, attritor grinding, two roll milling to disperse thepigments. The mill base is blended with the film-forming constituents.

Any of the conventional pigments used in coating compositions can beutilized in the composition such as the following: metallic oxides, suchas titanium dioxide, zinc oxide, iron oxide and the like, metalhydroxide, metal flakes such as aluminum flake, chromates, such as leadchromate, sulfides, sulfates, carbonates, carbon black, silica, talc,china clay, phthalocyanine blues and greens, organo reds, organo maroonsand other organic pigments and dyes.

The coating composition can be used as a clear finish over a coloredpigmented finish.

To improve weatherability of the clear finish of the coatingcomposition, about 0.1-5%, by weight, based on the weight of the binder,of an ultraviolet light stabilizer or a combination of ultraviolet lightstabilizers can be added. These stabilizers include ultraviolet lightabsorbers, screeners, quenchers and specific hindered amine lightstabilizers. Also, about 0.1-5% by weight, based on the weight of thebinder, of an antioxidant can be added.

Typical ultraviolet light stabilizers that are useful are as follows:

Benzophenones such as hydroxydodecylbenzophenone,2,4-dihydroxybenzophenone, hydroxy-benzophenones containing sulfonicacid groups, 2,4-dihydroxy-3'-5'-di-t-butylbenzophenone,2,2',4'-trihydroxybenzophenone esters of dicarboxylic acids,2-hydroxy-4-acryloxyethoxybenzophenone, aliphatic mono-esters of2,2',4-trihydroxy-4'-alkoxybenzophenone,2-hydroxy-4-methoxy-2'-carboxybenzophenone;

Triazoles such as 2-phenyl-4-(2'-4'-dihydroxybenzoyl)triazoles,substituted benzotriazoles such as hydroxyphenyltriazoles such as2-(2'hydroxy-5'-methylphenyl) benzotriazole,2-(2'hydroxyphenyl)benzotriazole,2-(2'-hydroxy-5'-octylphenyl)naphthatriazole;

Triazines such as 3,5-dialkyl-4-hydroxyphenyl derivatives of triazine,sulfur-containing derivatives of dialkyl-4-hydroxyphenyltriazines,hydroxyphenyl-1,3,5-triazines and such triazines containing sulfonicacid groups, aryl-1,3,5-triazines. orthohydroxyaryl-s-triazine;

Benzoates such as dibenzoate of diphenylolpropane, t-butyl benzoate ofdiphenylolpropane, nonyl phenyl benzoate, octyl phenyl benzoate,resorcinol dibenzoate.

Other ultraviolet light stabilizers that can be used include lower alkylthiomethylene-containing phenols, substituted benzenes such as1,3-bis(2'-hydroxybenzoyl)benzene, metal derivatives of3,5,-di-t-butyl-4-hydroxyphenylpropionic acid, asymmetrical oxalic aciddiarylamides, alkylhydroxyphenylthioalkanoic acid esters,dialkylhydroxyphenylalkanoic acid esters of di- and tri-pentaerythritol,phenyl- and naphthlene-substituted oxalic acid diamides,methyl-β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate,α,α'-bis(2-hydroxy-phenyl)diisopropylbenzene,3,5'-dibromo-2'-hydroxy-acetophenone, ester derivatives of4,4-bis(4'-hydroxy-phenyl)pentaonic acid wherein there is at least oneunsubstituted position ortho to the aromatic hydroxyl groups,organophosphorus sulfides such asbis(diphenyl-phosphinothioyl)monosulfide andbis(diphenyl-phosphinothioyl)disulfide,4-benzoyl-6-(dialkylhydroxybenzyl)resorcinol,bis(3-hydroxy-4-benzoylphenoxy)diphenylsilane,bis(3-hydroxy-4-benzoylphenoxy)dialkylsilane, 1,8-naphthalimides,α-cyano-β,β-diphenylacrylic acid derivatives,bis(2-benzoxazolyl)alkanes, bis(2-naphthoxazolyl)alkanes, methylenemalonitriles containing aryl and heterocyclic substitutes, alkylenebis(dithio)carbamate, 4-benzoyl-3-hydroxyphenoxyethyl acrylate,4-benzoyl-3-hydroxyphenoxyethyl methacrylate, aryl or alkyl-substitutedacrylonitriles, 3-methyl-5-isopropylphenyl-6-hydroxycourmarone,8-acetyl--dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro(4,5)decanol-2,4-dione.

Particularly useful ultraviolet light stabilizers that can be used arehindered amines of piperidyl derivatives such as those disclosed inMurayama et al., U.S. Pat. No. 4,061,616, issued Dec. 6, 1977, column 2,line 65, through column 4, line 2, and nickel compounds such as[1-phenyl-3-methyl-4-decanoylpyrazolate(5)]-Ni,bis[phenyldithiocarbamato]-Ni(II), and others listed in the abovePatent, column 8, line 44 through line 55.

The following blend of ultraviolet light stabilizers is particularlypreferred 2-[2'-hydroxy-3'-5'-1(1-1-dimethyl-propyl)phenyl]benzotriazoleandbis-[4-(1,2,2,6,6-pentamethylpiperidyl)]2-butyl-2-[(3,5-t-butyl-4-hydroxyphenyl)methyl]propanedioate.The stabilizers can be used in any ratio however, a 1:1 ratio ofbenzotriazole to propanedioate is preferred.

Another useful blend of ultraviolet light stabilizers is2-(benzotriazole-2-VL)-4,6-bis(methylethyl-1-phenyl ethyl)phenol, and2(3-hydroxy-3,5'-ditert amyl phenyl) benzotriazole.

Generally, the clear coating composition of this invention is applied bycoventional spraying techniques, preferably electrostatic spraying isused, to a color or base coat of an automobile or truck. The coating iscured and the resulting clear coat is about 1-5 mils thick preferably1-2 mils thick and has excellent gloss, good adhesion to the color coatand excellent weatherability.

The following examples illustrate the invention. All parts andpercentages are on a weight basis unless indicated otherwise. Molecularweights are determined by gel permeation chromatography using polymethylmethacrylate as the standard.

EXAMPLE 1

Polymer Solution A was prepared by charging the following constituentsinto a reaction vessel equipped with a stirrer, reflux condenser and aheating mantle:

    ______________________________________                                                             Parts By                                                                      Weight                                                   ______________________________________                                        Portion 1                                                                     Butyl acetate           78                                                    Portion 2                                                                     1,1 Azobis(cyclohexane carbonitrile)                                                                  55                                                    Toluene                550                                                    Portion 3                                                                     Styrene monomer        494                                                    Ethyl methacrylate monomer                                                                           494                                                    Lauryl methacrylate monomer                                                                          395                                                    Hydroxy ethyl acrylate monomer                                                                       592                                                    Total                  2658                                                   ______________________________________                                    

Portion 1 was heated to its reflux temperature. After Portion 2 wasmixed, it was added at a rate of 1 ml/min. over an 8 hour period.

Portion 3 was premixed and added simultaneously with portion 2 at a rateof 5 ml/min over a 7 hour period.

The resulting polymer solution had a polymer solids content of 65% andhad a Gardner Holdt viscosity measured at 25° C. of Z5. The polymer hadthe following composition 25% styrene, 25% ethyl methacrylate, 20%lauryl methacrylate, 30% hydroxyethyl acrylate and had an acid number of1.8 and a weight average molecular weight of 37,000 and a number averagemolecular weight of 14,000.

Coating composition A was prepared by blending together the followingconstituents:

    ______________________________________                                                          Parts By                                                                      Weight                                                      ______________________________________                                        Polymer Solution A  100.00                                                    (prepared above)                                                              "Desmodur" 3390      38.88                                                    (isocyanaurate trimer of                                                      hexamethylene diisocyanate)                                                   Methyl isobutyl ketone                                                                             30.00                                                    Stannous octoate     0.12                                                     Total               170.00                                                    ______________________________________                                    

A 10 mil thick layer of the resulting coating composition was drawn downon a glass panel with a wire wound rod and then placed in a chambercontaining a 1500 ppm concentration of dimethyl aminoethanol vapors at35° C. for about 4 minutes and then air was blown over the panel forabout 10 minutes. The resulting film did not cure and remained tacky andsoft.

Polymer Solution B prepared by charging the following constituents intoa reaction vessel equipped as above:

    ______________________________________                                                             Parts By                                                                      Weight                                                   ______________________________________                                        Portion 1                                                                     Butyl acetate          478                                                    Portion 2                                                                     Toluene                368                                                    1,1 Azo-bis(cyclohexane carbonitrile)                                                                 55                                                    Portion 3                                                                     4-Vinyl pyridine monomer                                                                              75                                                    Styrene monomer        419                                                    Ethyl methacrylate monomer                                                                           494                                                    Lauryl methacrylate monomer                                                                          395                                                    Hydroxy ethyl acrylate monomer                                                                       592                                                    Total                  2876                                                   ______________________________________                                    

Portion 1 was heated to its reflux temperature. After portion 2 wasmixed, it was added at a rate of 1 ml/min over an 8 hour period. Portion3 was premixed and added simultaneously with portion 2 at a rate of 5ml/min over a 7 hour period.

The resulting polymer solution had a polymer solids content of 72.7% andhad a Gardner Holdt viscosity measured at 25° C. of Z-6.

The polymer had the following composition 3.8% vinyl pyridine 21.2%styrene, 25% ethyl methacrylate, 20% lauryl methacrylate, 30%hydroxyethyl acrylate and had an acid number of 1.8 and a weight averagemolecular weight of 29,000 and a number average molecular weight of11,000.

Coating composition B was prepared by blending together the followingconstituents:

    ______________________________________                                                          Parts By                                                                      Weight                                                      ______________________________________                                        Polymer Solution B  100.00                                                    (prepared above)                                                              "Desmodur" 3390      38.88                                                    (isocyanaurate trimer of                                                      hexamethylene diisocyanate)                                                   Methyl isobutyl ketone                                                                             30.00                                                    Stannous octoate     0.12                                                     Total               170.00                                                    ______________________________________                                    

A 10 mil thick layer of the resulting coating composition was drawn downon a glass panel with a wire wound rod an then placed in a chambercontaining a 1500 ppm of dimethyl aminoethanol vapors at 35° C. forabout 4 minutes and then air was blown over the panel for about 10minutes.

The resulting film was tack free, hard and tough and was resistant tosolvents such as methyl isobutyl ketone.

Coating composition B was reduced with methyl isobutyl ketone to a sprayviscosity of 25 seconds using a No. 2 Zahn cup and sprayed onto primedflexible panels of a reaction injection molded urethane that were coatedwith a pigmented flexible acrylic basecoat. One coated panel was placedin a chamber containing dimethyl amino ethanol vapors at the abovedescribed concentration and temperature for 4 minutes and then air wasblown over the panel for 10 minutes. Another coated panel after beingexposed to the dimethyl amino ethanol was baked at 82° C. for 5 minutes.A third coated panel was not subjected to the amine vapors but baked at82° C. for 5 minutes.

In each case a clear coating was formed that was tack free, toughflexible, had a good gloss, had excellent adhesion to the substrate anda pencil hardness of 2H.

EXAMPLE 2

The following constituents were charged into a reaction vessel equippedas in Example 1:

    ______________________________________                                                           Parts By                                                                      Weight                                                     ______________________________________                                        Portion 1                                                                     Methyl amyl ketone   543.24                                                   Portion 2                                                                     Methyl amyl ketone   196.80                                                   t-Butyl peracetate    88.20                                                   Portion 3                                                                     Methacrylic acid monomer                                                                            73.16                                                   Styrene monomer      354.28                                                   Ethyl methacrylate monomer                                                                         457.47                                                   Lauryl methacrylate monomer                                                                        366.00                                                   Hydroxy ethyl acrylate monomer                                                                     548.88                                                   Total                2628.03                                                  ______________________________________                                    

Portion 1 was heated to its reflux temperature. After Portion 2 wasmixed, it was added at a rate of 2 ml/min over a 165 minute period.Portion 3 was premixed and added simultaneously with Portion 2 at a rateof 13 ml/min over a 150 minute period.

The resulting polymer solution had a polymer solids content of 69% andhad a Gardner Holdt viscosity measured at 25° C. of 24. The polymer hadthe following composition 4.1% methacrylic acid, 19.7% styrene, 25.4%ethyl methacrylate, 20.3% lauryl methacrylate, 30.5% hydroxyethylacrylate and had an acid number of about 30, a hydroxyl number of about180 and a weight average molecular weight of 9,500 and a number averagemolecular weight of 5,000.

The above polymer solution was reacted with propylene imine as followsto form an iminated polymer solution:

    ______________________________________                                                            Parts By                                                                      Weight                                                    ______________________________________                                        Portion 1                                                                     Polymer solution (prepared above)                                                                   200.0                                                   Portion 2                                                                     Isopropanol           800.0                                                   Propyleneimine         40.8                                                   Total                 1040.8                                                  ______________________________________                                    

Portion 2 was premixed and then added to Portion 1 and heated to 60° C.and held at this temperature for 8 hours. An acetic acid solution wasadded to react with any residual propylene imine and then the resultingby product was stripped off using conventional techniques.

A coating composition C was prepared by blending the followingconstituents:

    ______________________________________                                                                Parts By                                                                      Weight                                                ______________________________________                                        Portion 1                                                                     Polymer Solution B (prepared in Example 1)                                                              46.4                                                Portion 2                                                                     Iminated polymer solution (prepared above)                                                              46.4                                                Methyl isobutyl ketone    40.0                                                Acetyl acetone             4.0                                                "Desmodur" 3390 (described in Example 1)                                                                38.8                                                Portion 3                                                                     Stannous Octoate           0.2                                                Total                     175.67                                              ______________________________________                                    

Portion 2 was premixed and blended with Portion 1 and then Portion 3 wasadded and mixed to form a coating composition.

The resulting composition was reduced to a spray viscosity with methylisobutyl ketone and sprayed onto primed steel panels. One coated panelwas allowed to dry and cure at ambient temperatures. The coating wastack free in about 30 minutes and after 6 hours had a pencil hardness of2H. A second coated panel was flash dried for about 8 minutes and thenbaked for 5 minutes at 82° C. The resulting coating was about 2 milsthick and had a pencil hardness of 2H.

A vapor curable composition was formed by blending together thefollowing constituents:

    ______________________________________                                                               Parts By                                                                      Weight                                                 ______________________________________                                        Portion 1                                                                     Iminated polymer solution (prepared above)                                                             46.4                                                 Polymer solution (prepared in Example 1)                                                               46.4                                                 Portion 2                                                                     "Desmodur" 3390 (described in Example 1)                                                               38.8                                                 Methyl isobutyl ketone   48.7                                                 Portion 3                                                                     Stannous octoate          0.2                                                 Total                    180.5                                                ______________________________________                                    

The resulting coating composition was drawn down on glass panels using a10 HL blade and flash dried for 2 minutes and placed in a chambercontaining about 1500 ppm dimethyl amino ethanol at 38° C. for about 4minutes and air then was blown over the panels for 10 minutes. A tackfree, hard, tough and sandable coating was obtained.

EXAMPLE 3

The following constituents were charged into a reaction vessel equippedas in Example 1:

    ______________________________________                                                               Parts By                                                                      Weight                                                 ______________________________________                                        Portion 1                                                                     Methyl amyl ketone       513.00                                               Portion 2                                                                     Xylene                   550.00                                               1,1 Azobis-cyclohexane carbonitrile                                                                     55.00                                               Portion 3                                                                     Styrene monomer          375.25                                               Ethyl methacrylate monomer                                                                             414.75                                               Lauryl methacrylate monomer                                                                            316.00                                               Hydroxy ethyl acrylate monomer                                                                         740.00                                               t-Butyl amino ethyl methacrylate monomer                                                               157.40                                               Total                    3121.40                                              ______________________________________                                    

Portion 1 was heated to 145° C. and held at this temperature. AfterPortion 2 was mixed, it was added at a rate of 1 ml/min over an 8 hoursperiod. Portion 3 was premixed and added simultaneously with Portion 2at a rate of 5 ml/min over a 7 hour period.

The resulting polymer solution had a polymer solids content of about 63%and had a Gardner Holdt viscosity measured at 25° C. of Z5+1/4. Thepolymer had the following composition: 18.27% styrene, 20.20% ethylmethacrylate, 15.39% lauryl methacrylate, 38.47% hydroxyethyl acruylateand 7.67% t-butyl amino ethyl methacrylate had an acid number of 5 and aweight average molecular weight of 37,000 and a number average molecularweight of 6,300.

A coating composition was prepared by blending together the followingconstituents:

    ______________________________________                                                               Parts By                                                                      Weight                                                 ______________________________________                                        Portion 1                                                                     Polymer solution (prepared above)                                                                      500.00                                               Tinuvin 900 (hydroxy phenyl                                                                             15.35                                               benzotriazole U.V. light absorber)                                            Tinuvin 292 (hindered amine light stabilizer)                                                           11.55                                               Ethyl isobutyl ketone    360.00                                               Portion 2                                                                     "Desmodur" 3390 (described in Example 1)                                                               194.30                                               Stannous octoate          1.00                                                Ethyl acetate (urethane grade)                                                                         200.00                                               Total                    1282.20                                              ______________________________________                                    

Portion 1 was mixed and then portion 2 was mixed and added to portion 1and thoroughly mixed with portion 1.

The resulting composition was sprayed onto a primed steel substratecoated with a silver acrylic enamel base coat and then placed in achamber containing about 1500 ppm of dimethyl aminoethanol at 38° C. forabout 4 minutes. Air was blown over the panel for about 10 minutes. Theeresulting clear coating was about 2.0-2.2 mils thick, had excellent tapeadhesion, sandability, gloss and hardness.

The above coating composition was sprayed onto another primed steelpanel coated with a water based silver acrylic enamel base coat andflash dried for about 8 minutes and then baked for 5 minutes at about82° C. The resulting clear coating was about 2.0-2 mils thick, hadexcellent adhesion to the base coat, good gloss and hardness.

The above coating composition was sprayed onto a third panel of a primedflexible panel of a reaction injection molded urethane coated with awhite pigmented flexible acrylic base coat and placed in an aminecontaining chamber, described above, for same time and temperature asshown above and air was blown over the panels for 10 minutes. Theresulting clear coating was about 2.0-2.2 mils thick, had excellentadhesion to the base coat, good gloss and hardness.

We claim:
 1. A coating composition curable by a vaporous amine catalystcomprising about 20-80% by weight of film forming binder andcorrespondingly about 80-20% by weight of a liquid carrier; wherein thebinder consists essentially ofA. an acrylic polymer containing hydroxylgroups and amine containing groups selected from the group consisting ofsecondary amine groups, tertiary amine groups, pyridine groups, aminoester groups, hydroxy aminoester groups and the polymer has a weightaverage molecular weight of about 2,000-50,000 determined by gelpermeation chromatography using polymethyl methacrylate as the standardand wherein the acrylic polymer consists essentially of (1) polymerizedmonomers of an alkyl methacrylate or an alkyl acrylate and mixturesthereof or wherein the alkyl groups have 1-12 carbon atoms, (2)polymerized monomers of hydroxyl alkyl methacrylate or hydroxy alkylacrylate or mixtures thereof wherein the alkyl groups have 2-4 carbonatoms and (3) polymerized ethylenically unsaturated amine containingmonomer; and B. an aliphatic polyisocyanate.
 2. The coating compositionof claim 1 in which the acrylic polymer contains about 0.1-50% by weightof polymerized styrene.
 3. The coating composition of claim 1 in whichthe binder consists essentially of 40-90% by weight of the acrylicpolymer and 10-60% by weight of aliphatic polyisocyanate.
 4. The coatingcomposition of claim 2 in which the acrylic polymer consists essentiallyof polymerized constituents of about(1) 10-30% by weight, based on theweight of the acrylic polymer, of styrene or methyl methacrylate, (2)1-25% by weight, based on the weight of the acrylic polymer, of an aminecontaining ethylenically unsaturated monomers, (3) 30-70% by weight,based on the weight of the acrylic polymer, of alkyl methacrylate, alkylacrylate or mixtures thereof, each having 2-12 carbon atoms in the alkylgroup and (4) 20-40% by weight, based on the weight of the acrylicpolymer, of hydroxy alkyl acrylate or hydroxy alkyl methacrylate, eachhaving 2-4 carbon atoms in the alkyl group.
 5. The coating compositionof claim 4 in which the acrylic polymer consists essentially of styrene,vinyl pyridine, ethyl methacrylate, lauryl methacrylate and hydroxyethyl acrylate.
 6. The coating composition of claim 4 in which thealiphatic polyisocyanate is the trimer of hexamethylene diisocyanate. 7.The coating composition of claim 4 in which the acrylic polymer consistsessentially of styrene, ethyl methacrylate, lauryl methacrylate, hydroxyethyl acrylate and methacrylic acid post reacted with propylene imine toform pendent amino ester groups.
 8. The coating composition of claim 4in which the acrylic polymer consists essentially of styrene, ethylmethacrylate, lauryl methacrylate, hydroxy ethyl acrylate and butylamino ethyl methacrylate.
 9. A coating composition comprising 20-80% byweight of film forming binder and correspondingly, 80-20% by weight ofliquid carrier; wherein the binder consists essentially of aboutA.40-90% by weight of an acrylic polymer consisting essentially ofpolymerized constituents of about(1) 10-30% by weight, based on theweight of the acrylic polymer of styrene or methyl methacrylate, (2)1-25% by weight, based on the weight of the acrylic polymer, of an aminecontaining ethylenically unsaturated monomers. (3) 30-70% by weight,based on the weight of the acrylic polymer, of alkyl methacrylate, alkylacrylate or mixtures thereof, each having 2-12 carbon atoms in the alkylgroup and (4) 20-40% by weight, based on the weight of the acrylicpolymer, of hydroxy alkyl methacrylate or hydroxy alkyl acrylate, eachhaving 2-4 carbon atoms in the alkyl group. B. 10-60% by weight, basedon the weight of the binder, of an aliphatic polyisocyanate.
 10. Thecoating composition of claim 9 in which the acrylic polymer consistsessentially of polymerized monomers of styrene, vinyl pyridine, ethylmethacrylate, lauryl methacrylate and hydroxy ethyl acrylate and inwhich the aliphatic polyisocyanate is the trimer of hexamethylenediisocyanate.
 11. The coating composition of claim 9 in which theacrylic polymer consists essentially of polymerized monomers of styrene,ethyl methacrylate, lauryl methacrylate, hydroxy ethyl acrylate andmethacrylic acid post reacted with propylene imine to form pendant aminoester groups and in which the aliphatic polyisocyanate is the trimer ofhexamethylene diisocyanate.
 12. The coating composition of claim 9 inwhich the acrylic polymer consists essentially of polymerized monomersof styrene, ethyl methacrylate, lauryl methacrylate, hydroxy ethylacrylate and butyl amino ethyl methacrylate and in which the aliphaticpolyisocyanate is the trimer of hexamethylene diisocyanate.
 13. Thecoating composition of claim 9, containing pigments in a pigment tobinder weight ratio of about 1/100 to about 100/100 and in which theliquid carrier is an organic solvent for the binder.